1. Technical Field
The present invention relates to an operation apparatus for controlling musical sound properties such as timbre, volume, various effects, etc. of the musical sound on an electronic musical instrument.
2. Prior Art
There are many types of electronic musical instruments including not only electronic keyboard instruments such as an electronic organ, a synthesizer, etc., but also an electronic drum, a rhythm machine, a sequencer, an electronic wind instrument, a MIDI controller, etc. equipped with operation elements (operation keys).
For example, a key of an electronic keyboard instrument functions as an operation element for generating a sound at a specified interval. This key is also used as a control operation element for diversifying the musical sound by varying the musical sound""s volume or timbre at the time of generating the sound or after sounding or by adding ornamental effects such as tremolo, vibrato, panning, repeated beat, etc. Magnitude of a press force may be controlled simultaneously with a key press operation for performance so that both the sound generation and its control are available, allowing versatile, unrestricted performance by means of so-called after-touch control. A typical mechanism for enabling this control uses all arranged keys or a plurality of keys within a given range as control operation elements. A pressure sensor senses a key pressure when or after a key is pressed, thereby realizing the musical sound control according to the key press. In such a mechanism, a band-shaped pressure sensor extends across the longitudinal array of control keys or interlocking members thereof, and is arranged at a position where a key pressure is applied. The pressure sensor outputs a signal corresponding to the key pressure applied to any one of the control keys. A control section controls the musical sound according to that signal.
However, such a band-shaped pressure sensor generally has a length equivalent to several keys to several tens of keys, increasing costs and time for manufacturing and installing the pressure sensor. Consequently, this also creates increased manufacturing costs of electronic keyboard instruments using this pressure sensor.
By contrast, there is proposed an after-touch control mechanism having a single sensor covering commonly over a plurality of keys (Examined Patent Publication (Kokoku) 55-35716). This mechanism has a keyboard support frame extending along an array of keys of a keyboard apparatus and makes this support frame rotatable vertically. A shutter plate is mounted on a given location of this support frame. The shutter plate is positioned between a lamp and a photoconductor both mounted on the instrument itself, constituting an optical sensor mechanism. When a key press action rotates the support frame in this mechanism, the shutter rotates according to the amount of the support frame rotation to vary a light volume reaching the photoconductor from the lamp. The mechanism provides a sound volume variation according to the key pressure. However, since this mechanism is provided with the support frame extending along the array of keys of the keyboard apparatus, pressing a key always moves the support frame, thereby causing a stiff touch and increasing manufacturing costs.
In addition, there is proposed a switch apparatus having a single member acting commonly on a plurality of operation elements (Japanese Patent Unexamined Publication No. Shou. 59-189515). On this apparatus, a plurality of operation elements constitute a slide switch which slides vertically along the array of the operation elements. An interlocking member such as a wire, a string, etc. extends along the array of the operation elements. The interlocking member is stretched by a spring and is connected to the operation elements. In this apparatus, when one operation element is slid from a neutral position, the interlocking member is bent in a V shape along the slide direction against a spring force. When another operation element is slid, this movement returns the former operation element to the neutral position. This mechanism moves only one operation element to the slide position, thereby simplifying a structure for selecting timbres of the electronic musical instrument. However, this switch apparatus just provides an on/off select function by sliding the operation element, not suited for accurate after-touch control in response to key pressures.
Further, the electronic musical instrument controls dynamics and ornamental effects of the sound by manipulating operation elements other than the keyboard. There is a demand for a mechanism which can easily and reliably perform these operations.
It is an object of the present invention to provide an operation apparatus for the electronic musical instrument capable for solving problems of the conventional technology and accurately implementing after-touch control and other musical sound controls with a simple structure.
In order to achieve the aforementioned objects, the present invention provides an operation apparatus responsive to a physical action for inputting a control parameter of a musical sound into an electronic musical instrument. The operation apparatus comprises a plurality of movable members individually responsive to the physical action to undergo a reciprocal movement, a frame that mounts the plurality of the movable members in aligned manner, a tension member having a length and a pair of ends, and being supported at both the ends by the frame to extend along the movable members such that each movable member may come into contact with the tension member during the course of the reciprocal movement of each movable member, a detector connected to the tension member for detecting a deflection of the tension member caused by the contact of the movable member and generating a signal corresponding to the detected deflection as the control parameter, and a support member arranged on the frame for supporting the tension member such that the support member acts on the tension member to restrict the deflection thereof around the movable member which contacts the tension member, thereby avoiding the deflection from spreading along the length of the tension member.
Preferably, the support member may be arranged between a pair of movable members which are aligned adjacently with one another. The support member may have a groove for receiving therein the tension member.
Preferably, the operation apparatus may further comprise an operating element manually operable for applying the physical action to the movable member, and a stopper provided on the frame for stopping the operating element, wherein the support member comprises a deformable soft part of the stopper. The operation apparatus may further comprise a soft cover member that covers the tension member and the support member disposed along the tension member against the movable members, and that has a flexibility capable of transmitting the reciprocal movement of each movable member to the tension member to create the deflection. The operation apparatus may further comprise an elastic member engaged between the frame and the end of the tension member for regulating the deflection of the tension member.